Mobile broadband composite devices that use WMC UFD for grouping interfaces into functions should implement Microsoft OS descriptors to load USBCCGP on Windows 8 and instruct USBCCGP to parse WMC UFD to create functions. Mobile broadband composite devices that use Interface Association Descriptors (IADs) for grouping interfaces into functions do not need to implement Microsoft OS descriptors to load USBCCGP.

MBIM functions that are backward compatible should implement Microsoft OS descriptors to load MBCD. MBIM functions that are not backward compatible do not need to implement Microsoft OS descriptors to load MBCD.

These scenarios are discussed in more detail throughout the MB Interface Model topics. The following table summarizes all of the Microsoft OS compatible IDs mentioned in these subtopics. For more information see Microsoft OS Descriptors.

Microsoft OS compatible IDs

Microsoft OS Compatible ID

Microsoft OS Sub Compatible ID

Required for Scenario

"CDC_WMC"

Loading USBCCGP on composite devices that use WMC UFD for grouping interfaces into functions

"MBIM"

Loading MBCD on MBIM backward-compatible function

"ALTRCFG"

Configuration number in ASCII

Identity morphing with IADs

"WMCALTR"

Configuration number in ASCII

Identity morphing with WMC UFD

The MB Interface Model in described further in the following subtopics: